Mr. L. Reeve on the Terebratulse. 169 



XX. — A Revision of the History, Synonymy, and Geographical 

 Distribution of the recent Terebratulse. By Lovell Reeve, 

 F.L.S., F.G.S. 



Forty years ago, when M. Valenciennes prepared for Lamarck, 

 who was already blind, the monograph of this genus for his 

 ' Histoire des Animaux sans Vertebres,' the shells of only twelve 

 or fourteen species of recent TerebratulcE had been observed, the 

 soft parts of only one, and the organization of the Brachiopods 

 generally was very imperfectly known. Although Linnseus 

 had remarked that the animal of T. caput-serpentis differs not 

 less from any other animal that he had found in shells, than 

 night from day — "animal quod intus conditur a vermibus qui 

 aliis in conchis omnibus sibi invicem fere sunt similes non dif- 

 fert minus quam a nocte dies,^' — the Terebratulce and their allies 

 were still arranged with the lamellibranchiate Conchifera. 



De Blainville, and subsequently, by a more elaborate investi- 

 gation. Professor Owen, ascertained that the branchise do not 

 exist in the form of lamellse, but are incorporated by a system 

 of vessels with the mantle-lobes. Along with the discovery of 

 the phenomenon that the mantle-lobes of the Brachiopods perform 

 not only the office of secreting the shell, but also that of respira- 

 tion, another peculiarity was observed, namely, that the valves are 

 differently placed from those of other bivalves with regard to 

 the position of the animal — that, in fact, they are not side-valves 

 connected dorsally by a cartilage and ligament, but dorsal and 

 ventral valves, connected, in the Terebratulce, by closely intei-- 

 locking tooth -like processes in relation with an internal apophy- 

 sial skeleton, and a complicated system of muscles to which 

 may be added a force acquired through the auimal's habit of 

 affixing itself to foreign bodies by a fibrous byssus-like tendon. 

 Another peculiarity which presented itself was the presence 

 of a pair of internal ciliated arms. The Brachiopods, even as 

 late as 1830, were arranged by Cuvier and his contemporaries 

 in immediate proximity to the Cirripedes : it had, however, 

 been observed that the ciliated arms of the Brachiopod are quite 

 distinct organs from the cirri of the Cirripede ; and Professor 

 Owen's beautifully detailed exposition of its anatomy removed 

 all doubt on the subject. Projecting from the mouth of the 

 animal on either side, they correspond (or, to speak scientifically, 

 are homologous) with the labial palps of other bivalves, pro- 

 longed, as it were, on muscular tubes, so as to require being 

 folded or coiled up. In Terebratula an internal bony skeleton 

 or a})ophysis is formed, proceeding from the hinge in connexion 

 with the dorsal valve, for the support of the arms ; and being 



Ann. ^ Mag. N. Hist. Ser. 3. Vol. vii. 12 



